[A/S] Re: Honda EU2000i generator

["Maurice Riggins" <maurice.riggins@xxxxxxxxxxxxxxxx>]

I don't have either, but am planning the dual 2000 route.  With a 
full tank, they're about 55 lbs and that's all I want to lift out of 
the 4X4 truck bed.  The 3000 weighs near 150 lbs fueled and there's 
no way we could get it out of the truck... which means the AC 
wouldn't be available when the truck isn't there... not good since we 
have pets who would remain in the trailer.

I've confirmed with two people who've tried it that the 2000 will NOT 
start a typical 13,500 btu AC, but two in parallel have no problem.

It would take a 2500 watt inverter to provide 20 amps to an AC unit.  
That inverter would be sucking 200 amps out of the batteries.  That's 
about what a starter motor on a large V-8 engine draws and you know 
how long one battery will last with that.  Even a 1500 watt inverter 
is sucking 136 amps out of the batteries when a 1000W microwave oven 
magnetron is powered (about 2/3 of the time on high).

Batteries are typically rated at a low amp draw... 5 amps for 
example.  Sometimes they use a 20 hour rate, i.e. 5A for a 100AH 
battery, 6A for a 120AH battery.  The amp-hour capacity goes down as 
discharge current increases.  While you might think 100AH battery 
would give 4 hours at 25A (100/25=4), in reality that might be down 
to 3.3 hours or so.  Inverters are hard on battery life.  Even a tiny 
200W one is pulling a total near 20A at its rated output and a 500W 
one is drawing 25A out of EACH battery in a pair, at its rated output.

If you want the batteries to have a useful life, you won't discharge 
them below 50%.  So the typical PAIR of Interstate Battery 85AH Group 
27 batteries only gives you 85AH usable, and that's at no more than a 
10A discharge rate total or 5A/battery.  Trojan sells a Group 27 12V 
battery with 115AH, which in a pair gives slightly more AH than two 
of their T-105 6V golf cart batteries in series... and unlike the 
golf cart battery, they'll fit in most standard RV battery 
compartments (where they'll be warmer and produce even more power 
than a pair of golf cart batteries cold on the tongue for example).  
You can put 4 T-105's in a series/parallel circuit to double their 
capacity, but you can put 4 of their 12V batteries in parallel to get 
more than the same thing.  Keep in mind that if a battery in a 
parallel circuit fails, at the most all you have to do is remove it, 
and you can continue to operate at reduced capacity.  If a battery in 
a series circuit fails, the whole circuit is dead.

Let's think about solar.  If you get one $500 mail-order, 120 watt 
(17V X 7A peak) Kyocera panel pointed due south and tilted to be 90 
degrees to the sun when it's about 2/3 up in the sky at your 
location, you can expect an average current of 5 amps over a 5 hour 
period on a long summer day.  It will peak at around noon but be 
lower in the morning and evening.  So it will produce about 25AH on 
the best days with optimum conditions.  And a panel laying flat on a 
trailer roof is FAR from optimal.  Current drops off dramatically as 
solar angle departs from 90 degrees in any direction.

You have to charge about 10% more than the discharge to get the 
batteries back to the same point, so you'll need FOUR of these panels 
to charge at 20A average to replace 85-90AH/day.  If you hope to have 
enough reserve for only one rainy day, that only allows you about 40-
45AH/day.

Something else to think about... no more shady campsites for you!  If 
you're lucky enough to find one with full exposure for charging, the 
same solar energy that's providing electricity is also heating up the 
trailer.  So plan on another at least one 50W panel for each 
Fantastic Vent you will run on medium (2.3A) to fight the heat during 
charging.  So with a controller, you have maybe $2500-$2700 in a 
solar system, and we haven't even included the cost of an inverter, 
which can be very expensive if you get a quality one in the 1500-
2500W range.

Now lets look at just the little Honda EU1000iA2 providing 120VAC.  
Your 12V converter can usually provide a minimum of 40 amps of DC 
power, and at that rate, even considering inefficiencies, the 
converter takes less than 5 amps of the little Honda's 7.5 
continuous. 

In only four hours of run time, it can provide a minimum of 160AH, 
more if you have a larger converter, i.e. 240AH with a 60W converter, 
which would charge a bank of four 115AH 12V batteries discharged 
close to 50%.  AND you can operate many 120V appliances, such as a 
vacuum cleaner during that time.  However, unless you have a 600W 
microwave (900W during "on" time) you'll want a EU2000 for that.

Solar is fine if you already have a generator, it makes the 
environmentalist in you feel good, and that's worth the money to 
you.  But even a four+ panel system that costs five times that of 
Honda's EU1000 only produces maybe one-fifth the power the tiny 
generator does in the same time period each day.

Just my thoughts on RV power...
--
Maurice
WBCCI 5446